Not Applicable
1. Field of the Invention
The present invention relates to a golf ball with a thermoset polyurethane cover. More specifically, the present invention relates to a dimple pattern for a golf ball with a thermoset polyurethane cover in which the dimple pattern has different sizes of dimples.
2. Description of the Related Art
Golfers realized perhaps as early as the 1800""s that golf balls with indented surfaces flew better than those with smooth surfaces. Hand-hammered gutta-percha golf balls could be purchased at least by the 1860""s, and golf balls with brambles (bumps rather than dents) were in style from the late 1800""s to 1908. In 1908, an Englishman, William Taylor, received a patent for a golf ball with indentations (dimples) that flew better ad more accurately than golf balls with brambles. A.G. Spalding and Bros., purchased the U.S. rights to the patent and introduced the GLORY ball featuring the TAYLOR dimples. Until the 1970s, the GLORY ball, and most other golf balls with dimples had 336 dimples of the same size using the same pattern, the ATTI pattern. The ATTI pattern was an octahedron pattern, split into eight concentric straight line rows, which was named after the main producer of molds for golf balls.
The only innovation related to the surface of a golf ball during this sixty year period came from Albert Penfold who invented a mesh-pattern golf ball for Dunlop. This pattern was invented in 1912 and was accepted until the 1930""s.
In the 1970""s, dimple pattern innovations appeared from the major golf ball manufacturers. In 1973, Titleist introduced an icosahedron pattern which divides the golf ball into twenty triangular regions. An icosahedron pattern was disclosed in British Patent Number 377,354 to John Vernon Pugh, however, this pattern had dimples lying on the equator of the golf ball which is typically the parting line of the mold for the golf ball. Nevertheless, the icosahedron pattern has become the dominant pattern on golf balls today.
In the late 1970s and the 1980""s the mathematicians of the major golf ball manufacturers focused their intention on increasing the dimpled surface area (the area covered by dimples) of a golf ball. The dimpled surface for the ATTI pattern golf balls was approximately 50%. In the 1970""s, the dimpled surface area increased to greater than 60% of the surface of a golf ball. Further breakthroughs increased the dimpled surface area to over 70%. U.S. Pat. No. 4,949,976 to William Gobush discloses a golf ball with 78% dimple coverage with up to 422 dimples. The 1990""s have seen the dimple surface area break into the 80% coverage.
The number of different dimples on a golf ball surface has also increased with the surface area coverage. The ATTI pattern disclosed a dimple pattern with only one size of dimple. The number of different types of dimples increased, with three different types of dimples becoming the preferred number of different types of dimples. U.S. Pat. No. 4,463 to Oka et al., discloses a dimple pattern with four different types of dimples on surface where the non-dimpled surface cannot contain an additional dimple. United Kingdom patent application number 2157959, to Steven Aoyama, discloses dimples with five different diameters. Further, William Gobush invented a cuboctahedron pattern that has dimples with eleven different diameters. See 500 Year of Golf Balls, Antique Trade Books, page 189. However, inventing dimple patterns with multiple dimples for a golf ball only has value if such a golf ball is commercialized and available for the typical golfer to play.
Additionally, dimple patterns have been based on the sectional shapes, such as octahedron, dodecahedron and icosahedron patterns. U.S. Pat. No. 5,201,522 discloses a golf ball dimple pattern having pentagonal formations with equally number of dimples therein. U.S. Pat. No. 4,880,241 discloses a golf ball dimple pattern having a modified icosahedron pattern wherein small triangular sections lie along the equator to provide a dimple-free equator.
Although there are hundreds of published patents related to golf ball dimple patterns, there still remains a need to improve upon current dimple patterns, particularly for golf balls with thermoset polyurethane covers. Golf balls with thermoset polyurethane covers such as the Maxfli REVOLUTION, the Maxfli HT, the Titleist PROFESSIONAL, the Titleist TOUR PRESTIGE, and the Slazenger RAM 420 all need to compensate for the inherent properties of the polyurethane material which include the increased spin, the higher drag levels, and manufacturing difficulties. There is still a need for a dimple pattern designed to maximize the aerodynamics of a golf ball with a thermoset polyurethane cover.
The present invention provides a novel dimple pattern that reduces high speed drag on a golf ball while increasing its low speed lift thereby providing a golf ball that travels greater distances. The present invention is able to accomplish this by providing multiples sets of dimples arranged in a pattern that covers as much as eighty-six percent of the surface of the golf ball.
One aspect of the present invention is a dimple pattern on a golf ball having a thermoset cover with a surface coated with at least a base coat. The preferred thermoset is polyurethane, however, those skilled in the art will recognize that other thermoset materials may be employed in practicing the present invention. The golf ball includes a plurality of different sets of dimples disposed on the surface. Each of the different sets of dimples has a different diameter than any other set of dimples. The depth of each of the dimples of the plurality of different sets of dimples is limited to 0.0060 inches from the chord of each dimple.
The depth of each of the dimples of the plurality of different sets of dimples may be between 0.0045 and 0.0060 inches from the chord. Each of the dimples of the plurality of different sets of dimples has an entry angle, and the entry angle of each dimple may be between 14 and 16 degrees. Each of the dimples of the plurality of different sets of dimples has an edge radius, and the edge radius of each dimple may be between 0.020 and 0.050 inches.
Another aspect of the present invention is a dimple pattern on a golf ball having a thermoset polyurethane cover in which the dimple pattern has at least five different sets of dimples. The golf ball includes first, second, third, fourth and fifth pluralities of dimples disposed on the surface. Each of the first plurality of dimples has a first diameter. Each of the second plurality of dimples has a second diameter that is greater than the first diameter. Each of the third plurality of dimples has a third diameter that is greater than the second diameter. Each of the fourth plurality of dimples has a fourth diameter that is greater than the third diameter. Each of the fifth plurality of dimples has a fifth diameter that is greater than the fourth diameter. The first, second, third, fourth and fifth pluralities of dimples cover at least eighty percent of the surface of the golf ball.
The golf ball may also include a sixth plurality of dimples disposed on the surface with each of the sixth plurality of dimples having a sixth diameter that is greater than the fifth diameter. The first, second, third, fourth, fifth and sixth pluralities of dimples cover at least eighty-three percent of the surface of the golf ball.
The golf ball may further include at least one seventh dimple disposed on the surface. The at least one seventh dimple has a seventh diameter that is less than the first diameter. The first, second, third, fourth, fifth and sixth pluralities of dimples and the at least one seventh dimple cover at least eighty-six percent of the surface of the golf ball. The golf ball has an equator that divides the golf ball into a first hemisphere and a second hemisphere, and the first hemisphere may be unsymmetrical with the second hemisphere.
Another aspect of the present invention is a dimple pattern on a golf ball with a thermoset polyurethane cover that provides greater low speed lift and lower high speed drag. The golf ball includes a plurality of different sets of dimples disposed on the surface of the coated thermoset polyurethane cover. Each of the different sets of dimples having a different diameter than any other set of dimples. The plurality of different sets of dimples cover at least eighty-three percent of the surface of the golf ball. The golf ball has a lift coefficient greater than 0.20 at a Reynolds number of 70,000 and 2000 rpm, and a drag coefficient less than 0.232 at a Reynolds number of 180,000 and 3000 rpm.
Having briefly described the present invention, the above and further objects, features and advantages thereof will be recognized by those skilled in the pertinent art from the following detailed description of the invention when taken in conjunction with the accompanying drawings.